hdu2222(Keywords Search)

思路：题目中有若干个模式川和一个主串，问在主串中出现了几种模式串。显然就是模式串构成AC_Tree()，然后再去匹配主串。

因为new 了空间的，所以最后要delete释放。

// #pragma comment(linker, "/STACK:1024000000,1024000000")#include <iostream>#include <algorithm>#include <iomanip>#include <sstream>#include <string>#include <stack>#include <queue>#include <deque>#include <vector>#include <map>#include <set>#include <stdio.h>#include <string.h>#include <math.h>#include <stdlib.h>#include <limits.h>using namespace std;typedef long long LL;typedef unsigned long long ULL;typedef pair<int,int> ii;const int inf = 1 << 30;const int INF = 0x3f3f3f3f;const int MOD = 1e9 + 7;struct node{int cnt;struct node* fail;struct node* nxt[26];node(){fail = NULL;for (int i=0;i<26;i++)nxt[i]=NULL;cnt = 0;/*中间节点*/}};struct node* root;char keyword[55],str[1000005];/*构建字典树*/void build(char *str){struct node *p=p=root;int index;for (;*str !='\0';str++){index = *str - 'a';if (p->nxt[index] == NULL) p->nxt[index] = new node();p = p->nxt[index];}p->cnt++;}/*构建失败指针*/void AC_tree(){queue<node*> que;root->fail = NULL;struct node *p,*tmp;/*i,j*/que.push(root);while(!que.empty()){p = que.front();//ique.pop();for (int i=0;i<26;i++){if (p->nxt[i] != NULL){tmp = p->fail;//jwhile(tmp != NULL){if (tmp->nxt[i] != NULL){p->nxt[i]->fail = tmp->nxt[i];break;}tmp = tmp->fail;}if (tmp == NULL)p->nxt[i]->fail = root;que.push(p->nxt[i]);}}}}int find(char *str){int index;int sum = 0;struct node *p,*tmp;p = root;for (;*str!='\0';str++){index = *str - 'a';while(p->nxt[index] == NULL && p != root)p=p->fail;p = p->nxt[index];if (p == NULL)p = root;tmp = p;while(tmp != root && tmp->cnt != -1){sum += tmp->cnt;tmp->cnt = -1;tmp = tmp->fail;}}return sum;}void del(struct node* root){for (int i=0;i<26;i++){if (root->nxt[i] != NULL)del(root->nxt[i]);}delete root;}int main(){// freopen("in.txt","r",stdin);// freopen("out.txt","w",stdout);int T, n;while(scanf("%d",&T) != EOF){while(T--){root = new node();scanf("%d",&n);getchar();while(n--){scanf("%s",keyword);build(keyword);}AC_tree();scanf("%s",str);printf("%d\n",find(str));del(root);}}return 0;}